The Blue Dots

When you've finished the missions or are just not in the mood for following orders, have a look around for items(the blue dots). This is useful, as it unlocks safehouses, and it also helps you get higher ranks for the geurillas and the riojas, so when you die you don't have to walk/ drive/ fly/ swim miles to get to where you were. Also the blue dots are virtually everywhere (when you have collected most of them, look on the map on the SELECT menu and zoom as far in as possible so you can plot a course for those little hidden dots). I also recommend that you use a helicopter (either find it or get a heavy drop) because it gets you to places you can't go on foot (ex. mountains)

Sweet Jets And Helicopters

The planes aren't just in the airports, they're in the military bases. You get fast jets and cool helicopters with weapons in the military bases.